Remove or Retain the PCL in TKA?
In the world of total knee arthroplasty (TKA), the arguments about retaining the posterior cruciate ligament (PCL) versus stabilizing the knee with posterior-stabilized components have raged for more than 30 years. The number of cohort studies and controlled trials attempting to clarify the issue have been too high to count. In the July 5, 2017 issue of The Journal, Vertullo et al. use the power of the Australian national joint registry to add additional important clinical information to the debate.
More than 62,000 TKA cases formed the substrate of this analysis. In a study-design twist, the revision-related outcomes were analyzed on the basis of the preference surgeons had for the two different design options, not on the basis of which prostheses were actually used. Consequently, there was a likelihood that the cohort of patients treated by surgeons who had a preference for posterior-stabilized designs would include some PCL-retained cases, and vice-versa. The authors claim that this “instrumental variable analysis” has “the capacity to remove the confounding by indication or disease severity against posterior-stabilized total knee replacements.” However, as with any registry study, there were still many confounding variables that could have influenced the revision rate, not the least of which is surgeon skill in component alignment and ligament tensioning.
Nevertheless, with selection bias minimized, Vertullo et al. found a real difference in revision rates favoring retention of the PCL. That finding does make biomechanical sense to this non-arthroplasty surgeon, who would expect less stress on the tibial component-bone interface at the extremes of knee motion with the PCL-retaining procedure.
Biomechanics notwithstanding, I think this very large registry-based arthroplasty study will influence the debate going forward, but I doubt it will end the debate or that it will change the TKA practices of many surgeons worldwide. For a more definitive and potentially practice-changing resolution to this clinical conundrum, we’ll need a very large (2,000 to 3,000 patients in each arm) international trial where surgeons and patients accept randomization between these two choices.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
More Comparative Data on Surgical Approaches to THA
The May 17, 2017 edition of The Journal of Bone & Joint Surgery features a registry-based study by Mjaaland et al. comparing implant-survival/revision outcomes in total hip arthroplasty (THA) among four different surgical approaches:
- Minimally Invasive (MI) Anterior (n=2017)
- MI Anterolateral (n=2087)
- Conventional Posterior (n=5961)
- Conventional Direct Lateral (n=11,795)
Although the authors analyzed a whopping 21,860 THAs from 2008 to 2013, the findings are limited by the fact that all of those procedures used an uncemented stem.
Overall, the revision rates and risk of revision with the MI approaches were similar to those of the conventional approaches. There was a higher risk of revision due to infection in THAs that used the direct lateral approach than in THAs using the other three approaches. “To our knowledge,” the authors write, “this finding has not been previously described in the literature, and we do not have an explanation for it.” The authors also found a reduced risk of revision due to dislocation in THAs that used the MI anterior, MI anterolateral, and direct lateral approaches, relative to those using the posterior approach.
While the authors found all-cause risk of revision to be similar among all four approaches, they note that the follow-up in the study was relatively short (mean of 4.3 years) and that “additional studies are needed to determine whether there are long-term differences in implant survival.”
Long-Term Opioid Use Before TKA Raises Risk of Revision
Given the prevalence of opioid prescriptions, many patients present for total knee arthroplasty (TKA) having been on long-term opioid therapy. In the January 4, 2017 edition of The Journal of Bone & Joint Surgery, Ben-Ari et al. determined that patients taking opiate medications for more than three months prior to their TKA were significantly more likely than non-users of opioids to undergo revision surgery within a year after the index procedure.
Among the more than 32,000 TKA patients from Veterans Affairs (VA) databases included in the study, nearly 40% were long-term opioid users prior to surgery. Despite that high percentage, the authors found that chronic kidney disease was the leading risk factor for knee revision among the relevant variables they examined. And even though the authors used a sophisticated natural language/machine-learning tool to analyze postoperative notes, they found no association between long-term opioid use and the etiology of the revisions.
In a commentary accompanying the study, Michael Reich, MD and Richard Walker, MD, note that the study’s very specific VA demographic (94% male) may hamper the generalizability of the findings, especially because most TKAs are currently performed in women. Nevertheless, the commentators conclude that:
- “The study illuminates the value in limiting opioid use during the nonoperative treatment of patients with knee arthritis.”
- “Patients who are taking opioids when they present for TKA could reasonably be encouraged to decrease opioid use during preoperative preparation.”
- “Preoperative use of opioids should be considered among modifiable risk factors and comorbidities when deciding whether to perform TKA.”
JBJS Webinar: Effective Management of the Infected Total Joint
The incidence of primary total knee and hip arthroplasty is increasing steadily. While the success rates of these procedures are remarkable, failures do occur, and periprosthetic joint infection is the leading culprit in such failures. The standard treatment when deep infection strikes is a two-stage revision.
On Monday, November 14, 2016 at 8:00 PM EST, The Journal of Bone & Joint Surgery (JBJS) will host a complimentary webinar that examines prognostic factors affecting the success of two-stage revision arthroplasty for infected knees and hips.
- Tad M. Mabry, MD, coauthor of a matched cohort study in JBJS, will examine the impact of morbid obesity on the failure of two-stage revision TKA.
- JBJS author Antonia F. Chen, MD, will discuss results from a retrospective study that revealed an association between positive cultures at the time of knee/hip component reimplantation and the risk of subsequent treatment failure.
Moderated by JBJS Deputy Editor Charles R. Clark, MD, the webinar will include additional perspectives from two expert commentators—Daniel J. Berry, MD and Andrew A. Freiberg, MD. The last 15 minutes will be devoted to a live Q&A session, during which the audience can ask questions of all four panelists.
Seats are limited, so register now!
Long-Term Revision Rates after Cervical Spine Arthrodesis
Most studies looking into revision rates after cervical spine fusion follow patients for 2 to 5 years. But in the September 21, 2016 issue of JBJS, Derman et al. investigate revision rates—and risk factors for revision—with a follow-up of 16 years.
Analyzing New York State’s SPARCS all-payer database, the authors identified more than 87,000 patients who underwent a primary subaxial cervical arthrodesis from 1997 through 2012. During the study period, 7.7% of the patients underwent revision, with a median time to revision of 24.5 months.
Cervical arthrodeses performed with anterior-only approaches had a significantly higher probability of revision than those performed via posterior or circumferential approaches. The authors also found that the following characteristics were associated with an elevated revision risk:
- Patient age of 18 to 34 years
- White race
- Workers’ Compensation or Medicare (but not Medicaid) coverage
- Arthrodeses to address spinal stenosis, spondylosis, deformity, or neoplasm
Shorter arthrodeses (i.e., fewer fusion levels) and arthrodesis to address fractures were associated with relatively lower revision risks.
The authors conclude that “knowledge of these factors should help to promote exploration of strategies to reduce the prevalence of revision(s)…and to facilitate more accurate preoperative counseling of patients.”
Recent Comments